Machinery that provides for the continuous transport of dry webs of paper over multiple rollers and other components where the web's direction changes can be the cause of substantial dust generation. Dust that accumulates on the machinery can interfere with correct operation, lead to product quality problems in some circumstances, hinder maintenance, and may also present a fire hazard. Dust that is transferred into the air can also represent a fire hazard, and additionally can be breathed by workers.
Much effort has been directed to the development of dust hoods for sucking dust laden air from parts of such machines. However, such devices are themselves imperfect in operation and can require substantial power consumption.
In some applications it is important to remove entrained dust from air in the vicinity of a moving web and to remove dust from the web itself. This is commonly done by dust hoods and the like that use a combination of directed jets of air provided by a compressor and suction applied near the moving web.
Such installations are usually provided at critical points in the path of a moving web, for example near doctor blades that crepe (separate) a web of paper from the surface of a so-called Yankee drum. However, there are often locations in paper making and handling machinery where significant dust is generated by, for example, being entrained in a “boundary layer” of air moving with the web close to its surface or by being thrown off the web near rollers and the like, where it is undesirable or difficult to provide elaborate, costly, high-power consuming and bulky dust removal equipment.
There is thus a need for a method of controlling dust at such locations without these disadvantages or in which they are reduced. The present invention provides apparatus and methods which address this problem.
It is believed that the concepts are not limited in their application to paper processing machinery only.